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  • 1
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    First In-Situ Measurements of Plume Chemistry at Mount Garet Volcano, Island of Gaua (Vanuatu) (2020)
    MDPI
    Details
    Publication Date: 2020-11-25
    Description: Recent volcanic gas compilations have urged the need to expand in-situ plume measurements to poorly studied, remote volcanic regions. Despite being recognized as one of the main volcanic epicenters on the planet, the Vanuatu arc remains poorly characterized for its subaerial emissions and their chemical imprints. Here, we report on the first plume chemistry data for Mount Garet, on the island of Gaua, one of the few persistent volatile emitters along the Vanuatu arc. Data were collected with a multi-component gas analyzer system (multi-GAS) during a field campaign in December 2018. The average volcanic gas chemistry is characterized by mean molar CO2/SO2, H2O/SO2, H2S/SO2 and H2/SO2 ratios of 0.87, 47.2, 0.13 and 0.01, respectively. Molar proportions in the gas plume are estimated at 95.9 11.6, 1.8 0.5, 2.0 0.01, 0.26 0.02 and 0.06 0.01, for H2O, CO2, SO2, H2S and H2. Using the satellite-based 10-year (2005–2015) averaged SO2 flux of ~434 t d􀀀1 for Mt. Garet, we estimate a total volatile output of about 6482 t d􀀀1 (CO2 ~259 t d􀀀1; H2O ~5758 t d􀀀1; H2S ~30 t d􀀀1; H2 ~0.5 t d􀀀1). This may be representative of a quiescent, yet persistent degassing period at Mt. Garet; whilst, as indicated by SO2 flux reports for the 2009–2010 unrest, emissions can be much higher during eruptive episodes. Our estimated emission rates and gas composition for Mount Garet provide insightful information on volcanic gas signatures in the northernmost part of the Vanuatu Arc Segment. The apparent CO2-poor signature of high-temperature plume degassing at Mount Garet raises questions on the nature of sediments being subducted in this region of the arc and the possible role of the slab as the source of subaerial CO2. In order to better address the dynamics of along-arc volatile recycling, more volcanic gas surveys are needed focusing on northern Vanuatu volcanoes.
    Description: This research was conducted as part of the Trail by Fire II—Closing the Ring Project (PI: Y. Moussallam) funded by the National Geographic Society (grant number CP-122R-17), the Rolex Awards for Enterprise and the French national Research Institute for Development (IRD). J.L. also acknowledges travel funding support from Ministero dell’istruzione, dell’università e della ricerca (MIUR;) under grant n. PRIN2017-2017LMNLAW).
    Description: Published
    Description: id 7293
    Description: 4V. Processi pre-eruttivi
    Description: JCR Journal
    Keywords: Vanuatu ; Gaua ; Mount Garet ; Multi-GAS ; volcanic gas composition ; volatile fluxes ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    Characterisation of the magmatic signature in gas emissions from Turrialba Volcano, Costa Rica (2020)
    EGU - Copernicus
    Details
    Publication Date: 2020-11-25
    Description: The equilibrium composition of volcanic gaseswith their magma is often overprinted by interaction with ashallow hydrothermal system. Identifying the magmatic sig-nature of volcanic gases is critical to relate their composi-tion to properties of the magma (temperature,fO2, gas-meltsegregation depth). We report measurements of the chemi-cal composition and flux of the major gas species emittedfrom Turrialba Volcano during March 2013. Measurementswere made of two vents in the summit region, one of whichopened in 2010 and the other in 2012. We determined an av-erage SO2flux of 5.2±1.9 kg s−1using scanning ultravio-let spectroscopy, and molar proportions of H2O, CO2, SO2,HCl, CO and H2gases of 94.16, 4.03, 1.56, 0.23, 0.003 and0.009 % respectively by open-path Fourier transform infrared(FTIR) spectrometry and a multi-species gas-sensing system.Together, these data imply fluxes of 88, 8, 0.44, 5×10−3and1×10−3kg s−1for H2O, CO2, HCl, CO and H2respectively.Although H2S was detected, its concentration could not beresolved. HF was not detected. The chemical signature of thegas from both vents was found to be broadly similar. Follow-ing the opening of the 2010 and 2012 vents we found limitedto negligible interaction of the magmatic gas with the hy-drothermal system has occurred and the gas composition ofthe volcanic plume is broadly representative of equilibriumwith the magma. The time evolution of the gas composition,the continuous emission of large quantities of SO2, and thephysical evolution of the summit area with new vent open-ings and more frequent eruptions all point towards a continu-ous drying of the hydrothermal system at Turrialba’s summitat an apparently increasing rate.
    Description: This research was supported by the RoyalGeographical Society (with IBG) with a Geographical FieldworkGrant. Y. Moussallam and N. Peters were additionally supportedby the Philip Lake funds from the Department of Geography,University of Cambridge. Y. Moussallam acknowledges a researchgrant from Mazamas and support through ERC project #279790.We thank the NERC Field Spectroscopy Facility for the loanof their infrared spectrometer. A. Aiuppa acknowledges supportthrough ERC grant no. 305377 (BRIDGE)
    Description: Published
    Description: 1341–1350
    Description: 4V. Processi pre-eruttivi
    Description: JCR Journal
    Keywords: volcanic degassing ; Multi-GAS ; UV spectroscopy ; FTIR ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
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    Volcanic activity and gas emissions along the South Sandwich Arc (2021)
    Details
    Publication Date: 2021-01-12
    Description: The South Sandwich Volcanic Arc is one of the most remote and enigmatic arcs on Earth. Sporadic observations from rare cloudfree satellite images—and even rarer in situ reports—provide glimpses into a dynamic arc system characterised by persistent gas emissions and frequent eruptive activity. Our understanding of the state of volcanic activity along this arc is incomplete compared to arcs globally. To fill this gap, we present here detailed geological and volcanological observations made during an expedition to the South Sandwich Islands in January 2020.We report the first in situ measurements of gas chemistry, emission rate and carbon isotope composition from along the arc. We show that Mt. Michael on Saunders Island is a persistent source of gas emissions, releasing 145±59 t day−1 SO2 in a plume characterised by a CO2/SO2 molar ratio of 1.8 ± 0.2. Combining this CO2/SO2 ratio with our independent SO2 emission rate measured near simultaneously, we derive a CO2 flux of 179 ± 76 t day−1. Outgassing from low temperature (90–100 °C) fumaroles is pervasive at the active centres of Candlemas and Bellingshausen, with measured gas compositions indicative of interaction between magmatic fluids and hydrothermal systems. Carbon isotope measurements of dilute plume and fumarole gases from along the arc indicate a magmatic δ13C of − 4.5 ± 2.0‰. Interpreted most simply, this result suggests a carbon source dominated by mantle-derived carbon. However, based on a carbon mass balance from sediment core ODP 701, we show that mixing between depleted upper mantle and a subduction component composed of sediment and altered crust is also permissible.We conclude that, although remote, the South Sandwich Volcanic Arc is an ideal tectonic setting in which to explore geochemical processes in a young, developing arc.
    Description: This expedition was funded by public donations raised by Quark Expeditions Ltd., by the Government of South Georgia and the South Sandwich Islands (GSGSSI) and by individual contributions. This work was carried out under RAP 2019/025 issued by GSGSSI. EJL was supported by a Leverhulme Early Career Fellowship. A.A. and M.B. acknowledge funding from Miur (Grant N. 2017LMNLAW). K.W. acknowledges support from the Mount Everest Foundation (20-06)
    Description: Published
    Description: id 3
    Description: 4V. Processi pre-eruttivi
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Description: 1IT. Reti di monitoraggio e sorveglianza
    Description: JCR Journal
    Keywords: South Sandwich Volcanic Arc ; Volcanic gas emissions ; Volcanic activity ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
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    Dynamics of Outgassing and Plume Transport Revealed by Proximal Unmanned Aerial System (UAS) Measurements at Volcán Villarrica, Chile (2019)
    Details
    Publication Date: 2020-12-17
    Description: Volcanic gas emissions are intimately linked to the dynamics of magma ascent and outgassing and, on geological time scales, constitute an important source of volatiles to the Earth's atmosphere. Measurements of gas composition and flux are therefore critical to both volcano monitoring and to determining the contribution of volcanoes to global geochemical cycles. However, significant gaps remain in our global inventories of volcanic emissions, (particularly for CO2, which requires proximal sampling of a concentrated plume) for those volcanoes where the near‐vent region is hazardous or inaccessible. Unmanned Aerial Systems (UAS) provide a robust and effective solution to proximal sampling of dense volcanic plumes in extreme volcanic environments. Here we present gas compositional data acquired using a gas sensor payload aboard a UAS flown at Volcán Villarrica, Chile. We compare UAS‐derived gas time series to simultaneous crater rim multi‐GAS data and UV camera imagery to investigate early plume evolution. SO2 concentrations measured in the young proximal plume exhibit periodic variations that are well correlated with the concentrations of other species. By combining molar gas ratios (CO2/SO2 = 1.48–1.68, H2O/SO2 = 67–75, and H2O/CO2 = 45–51) with the SO2 flux (142 ± 17 t/day) from UV camera images, we derive CO2 and H2O fluxes of ~150 t/day and ~2,850 t/day, respectively. We observe good agreement between time‐averaged molar gas ratios obtained from simultaneous UAS‐ and ground‐based multi‐GAS acquisitions. However, the UAS measurements made in the young, less diluted plume reveal additional short‐term periodic structure that reflects active degassing through discrete, audible gas exhalations.
    Description: Published
    Description: 730-750
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Description: JCR Journal
    Keywords: UAS ; volcanic plume ; villarrica ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
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    Geochemical constraints on volatile sources and subsurface conditions at Mount Martin, Mount Mageik, and Trident Volcanoes, Katmai Volcanic Cluster, Alaska (2017)
    Details
    Publication Date: 2021-05-11
    Description: We use the chemical and isotopic composition of volcanic gases and steam condensate, in situ measurements of plume composition and remote measurements of SO2 flux to constrain volatile sources and characterize subvolcanic conditions at three persistently degassing and seismically active volcanoes within the Katmai Volcanic Cluster (KVC), Alaska:Mount Martin,Mount Mageik and Trident. In situ plume measurements of gas composition were collected at all three volcanoes usingMultiGAS instruments to calculate gas ratios (e.g. CO2/H2S, SO2/H2S and H2O/H2S), and remote measurements of SO2 column density were collected from Mount Martin and Mount Mageik by ultraviolet spectrometer systems to calculate SO2 fluxes. Fumaroles were directly sampled for chemical and isotopic composition from Mount Mageik and Trident. Mid Ocean Ridge Basalt (MORB)-like 3He/4He ratios (~7.2–7.6 Rc/RA) within Mount Mageik and Trident's fumarole emissions and a moderate SO2 flux (~75 t/d) from Mount Martin, combined with gas compositions dominated by H2O, CO2 and H2S from all three volcanoes, indicate magma degassing and active hydrothermal systems in the subsurface of these volcanoes. Mount Martin's gas emissions have the lowest CO2/H2S ratio (~2–4) and highest SO2 flux compared to the other KVC volcanoes, indicative of shallow magma degassing. Geothermometry techniques applied to Mount Mageik and Trident's fumarolic gas compositions suggest that their hydrothermal reservoirs are located at depths of ~0.2 and 4 km below the surface, respectively. Observations of an unusually reducing gas composition at Trident and organic material in the near-surface soils suggest that thermal decomposition of sediments may be influencing gas composition. When the measured gas compositions from Mount Mageik and Trident are compared with previous samples collected in the late 1990's, relatively stable magmatic-hydrothermal conditions are inferred forMountMageik,while gradual degassing of residual magma and contamination by shallow crustal fluids is inferred for Trident. The isotopic composition of volcanic gases emitted from Mount Mageik and Trident reflect mixing of subducted slab, mantle and crustal volatile sources, with organic sediment and carbonate being the predominant sources. Considering the close proximity of the target volcanoes in comparison with the depth to the subducted slab we speculate that Aleutian Arc volatiles are fed by a relatively homogeneous subducted fluid and that much of the apparent variability in volatile provenance can be explained by shallow crustal volatile sources and/or processes.
    Description: Published
    Description: 64-81
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: 3V. Proprietà dei magmi e dei prodotti vulcanici
    Description: JCR Journal
    Keywords: Katmai ; volcanic gases ; Mount Martin ; Mount Mageik ; Trident ; hydrothermal system ; arc volcano ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
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    Sulfur Degassing From Steam-Heated Crater Lakes: El Chichón (Chiapas, Mexico) and Víti (Iceland) (2019)
    Details
    Publication Date: 2021-06-22
    Description: The composition of the gases released by El Chichón (Chiapas, Mexico) and Víti (Askja volcano, Iceland) volcanic lakes is examined by Multi-GAS for the first time. Our results demonstrate that H2S and SO2 are degassed by these pH 2–3 lakes. We find higher CO2/H2S and H2/H2S ratios in the lakes’ emissions (31–5,685 and 0.6–35, respectively) than in the fumarolic gases feeding the lakes (13–33 and 0.08–0.5, respectively), evidencing that only a fraction (0.2–5.4% at El Chichón) of the H2S(g) contributed by the subaquatic fumaroles ultimately reaches the atmosphere. At El Chichón, we estimate a H2S output from the crater lake of 0.02–0.06 t/day. Curiously, SO2 is also detected at trace levels in the gases released from both lakes (0.003–0.3 ppmv).We propose that H2S supplied into the lakes initiates a series of complex oxidation reactions, having sulfite as an intermediate product, and ultimately leading to SO2 production and degassing.
    Description: Published
    Description: 7504-7513
    Description: 4V. Processi pre-eruttivi
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
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    Aerial strategies advance volcanic gas measurements at inaccessible, strongly degassing volcanoes (2020)
    AAAS
    Details
    Publication Date: 2021-06-07
    Description: Volcanic emissions are a critical pathway in Earth's carbon cycle. Here, we show that aerial measurements of volcanic gases using unoccupied aerial systems (UAS) transform our ability to measure and monitor plumes remotely and to constrain global volatile fluxes from volcanoes. Combining multi-scale measurements from ground-based remote sensing, long-range aerial sampling, and satellites, we present comprehensive gas fluxes-3760 ± [600, 310] tons day-1 CO2 and 5150 ± [730, 340] tons day-1 SO2-for a strong yet previously uncharacterized volcanic emitter: Manam, Papua New Guinea. The CO2/ST ratio of 1.07 ± 0.06 suggests a modest slab sediment contribution to the sub-arc mantle. We find that aerial strategies reduce uncertainties associated with ground-based remote sensing of SO2 flux and enable near-real-time measurements of plume chemistry and carbon isotope composition. Our data emphasize the need to account for time averaging of temporal variability in volcanic gas emissions in global flux estimates.
    Description: This research was enabled through the Alfred P. Sloan Foundation's support of the Deep Carbon Observatory Deep Earth Carbon Degassing program (DECADE). Part funding also came from the EPSRC CASCADE programme grant (EP/R009953/1). EJL was supported by a Leverhulme Trust Early Career Fellowship. KW was supported by the National Center for Nuclear Robotics (NCNR) EPSRC grant (EP/R02572X/1).
    Description: Published
    Description: eabb9103
    Description: 7TM.Sviluppo e Trasferimento Tecnologico
    Description: JCR Journal
    Keywords: UAS ; volcanic plume ; carbon cycle ; 04.08. Volcanology ; 05.04. Instrumentation and techniques of general interest
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
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    Isotopically (δ13C and δ18O) heavy volcanic plumes from Central Andean volcanoes: a field study (2018)
    Details
    Publication Date: 2020-11-20
    Description: Stable isotopes of carbon and oxygen in volcanic gases are key tracers of volatile transfer between Earth’s interior and atmosphere. Although important, these data are available for few volcanoes because they have traditionally been difficult to obtain and are usually measured on gas samples collected from fumaroles. We present new field measurements of bulk plume composition and stable isotopes (δ13CCO2 and δ18OH2O+ CO2) carried out at three northern Chilean volcanoes using MultiGAS and isotope ratio infrared spectroscopy. Carbon and oxygen in magmatic gas plumes of Lastarria and Isluga volcanoes have δ13C in CO2 of +0.76‰ to +0.77‰ (VPDB), similar to slab carbonate; and δ18O in the H2O + CO2 system ranging from +12.2‰ to +20.7‰ (VSMOW), suggesting significant contributions from altered slab pore water and carbonate. The hydrothermal plume at Tacora has lower δ13CCO2 of −3.2‰ and δ18OH2O+CO2 of +7.0‰, reflecting various scrubbing, kinetic fractionation, and contamination processes. We show the isotopic characterization of volcanic gases in the field to be a practical complement to traditional sampling methods, with the potential to remove sampling bias that is a risk when only a few samples from accessible fumaroles are used to characterize a given volcano’s volatile output. Our results indicate that there is a previously unrecognized, relatively heavy isotopic signature to bulk volcanic gas plumes in the Central Andes, which can be attributed to a strong influence from components of the subducting slab, but may also reflect some local crustal contamination. The techniques we describe open new avenues for quantifying the roles that subduction zones and arc volcanoes play in the global carbon cycle.
    Description: Published
    Description: 65
    Description: 3V. Proprietà dei magmi e dei prodotti vulcanici
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 9
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    Sustaining persistent lava lakes: Observations from high-resolution gas measurements at Villarrica volcano, Chile (2020)
    Elsevier
    Details
    Publication Date: 2020-11-25
    Description: Active lava lakes – as the exposed upper part of magmatic columns – are prime locations to investigate the conduit flow processes operating at active, degassing volcanoes. Persistent lava lakes require a constant influx of heat to sustain a molten state at the Earth's surface. Several mechanisms have been proposed to explain how such heat transfer can operate efficiently. These models make contrasting predictions with respect to the flow dynamics in volcanic conduits and should result in dissimilar volatile emissions at the surface. Here we look at high-frequency SO2 fluxes, plume composition, thermal emissions and aerial video footage from the Villarrica lava lake in order to determine the mechanism sustaining its activity. We found that while fluctuations are apparent in all datasets, none shows a stable periodic behaviour. These observations suggest a continuous influx of volatiles and magma to the Villarrica lava lake. We suggest that ascending volatile-rich and descending degassed magmas are efficiently mixed within the volcanic conduit, resulting in no clear periodic oscillations in the plume composition and flux. We compare our findings to those of other lava lakes where equivalent gas emission time-series have been acquired, and suggest that gas flux, magma viscosity and conduit geometry are key parameters determining which flow mechanism operates in a given volcanic conduit. The range of conduit flow regimes inferred from the few studied lava lakes gives a glimpse of the potentially wide spectrum of conduit flow dynamics operating at active volcanoes.
    Description: This research was conducted as part of the “Trail By Fire” expedition (PI: Y. Moussallam). The project was supported by the Royal Geographical Society (with the Institute of British Geographers) with the Land Rover Bursary; the Deep Carbon Observatory DECADE Initiative; Ocean Optics; Crowcon; Air Liquide; Thermo Fisher Scientific; Santander; Cactus Outdoor; Turbo Ace and Team Black Sheep. We thank Sebastien Carretier and Rose-Marie Ojeda together with IRD South-America personnel for all their logistical help. We further thank the CONAF and DGAC for their help. YM acknowledges support from the Scripps Institution of Oceanography Postdoctoral Fellowship program. CIS acknowledges a research startup grant from Victoria University of Wellington
    Description: Published
    Description: 237-247
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Description: JCR Journal
    Keywords: volcanic degassing ; Multi-GAS ; UAV ; Trail By Fire ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 10
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    Fuzzy cellular systems for a new computational paradigm (2020)
    Elsevier
    Details
    Publication Date: 2020-11-25
    Description: In this paper a new approach for processing arrays of data is proposed. It is based on fuzzy logic and the concepts of cellular computation. Arrays of simple, identical processing elements (called fuzzy cells) are defined by using fuzzy rules. Moreover, each fuzzy cell interacts with its local neighbors. The overall behavior of these locally interacting fuzzy systems is used to process arrays of data. Some examples of practical applications are proposed. Among these, the new approach is applied to image-processing problems, and to the simulation of heat diffusion phenomena.
    Description: This work was partially supported by the Italian National Research Council (C.N.R.) under the special project "Reti neurali per i sistemi di controllo".
    Description: Published
    Description: 47-52
    Description: 3IT. Calcolo scientifico
    Description: JCR Journal
    Keywords: fuzzy logic ; partial differential equations ; 05.09. Miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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